Expert? Lets just say i have made enough mistakes to know what not to do...
There are some new bottles out now that say they can be hot filled with max temp of 180f. Which is the bare minimum temp for hot fill. Previously, the bottles would melt with the heated sauce, or as the bottles cooled and contracted, the bottles would collapse.
If your copacker has a VERY accurate heated filling machine, it would be something to discuss with them.
Let us know how it goes and what you end up using. If there is a stable plastic bottle that can be hot filled, that would be Awesome!
Have fun!
Salsalady